Second-site mutagenesis was performed on the argonaute1-33 (ago1-33) hypomorphic mutant, which exhibits reduced sense transgene posttranscriptional gene silencing (S-PTGS). Mutations in FIERY1, a positive regulator of the cytoplasmic 5'-to-3' EXORIBONUCLEASE4 (XRN4), and in SUPERKILLER3 (SKI3), a member of the SKI complex that threads RNAs directly to the 3'-to-5' exoribonuclease of the cytopla...

Specific silencing of target genes can be induced in a variety of organisms by providing homologous double-stranded RNA molecules. In vivo, these molecules can be generated either by transcription of sequences having an inverted-repeat (IR) configuration or by simultaneous transcription of sense-antisense strands. Since IR constructs are difficult to prepare and can stimulate genomic rearrangem...

Post-transcriptional gene silencing (PTGS) involving small interfering RNA (siRNA)-directed degradation of RNA transcripts and transcriptional silencing via DNA methylation have each been proposed as mechanisms of genome defence against invading nucleic acids, such as transposons and viruses. Furthermore, recent data from plants indicates that many transposons are silenced via a combination of ...

BACKGROUND The association between DNA methylation and gene silencing has long been recognized; however, signals that initiate de novo methylation are largely unknown. In plants, recognition of RNAs that are inducers of posttranscriptional gene silencing (PTGS) can result in sequence-specific DNA methylation, and the aim of this work was to investigate whether heritable epigenetic changes can o...

A recently characterized calmodulin-like protein is an endogenous RNA silencing suppressor that suppresses sense-RNA induced post-transcriptional gene silencing (S-PTGS) and enhances virus infection, but the mechanism underlying calmodulin-like protein-mediated S-PTGS suppression is obscure. Here, we show that a calmodulin-like protein from Nicotiana benthamiana (NbCaM) interacts with Suppresso...

The RNA-dependent RNA polymerase (RdRP) qde-1 is an essential component of post-transcriptional gene silencing (PTGS), termed 'quelling' in the fungus Neurospora crassa. Here we show that the overexpression of QDE-1 results in a dramatic increase in the efficiency of quelling, with a concomitant net increase in the quantity of al-1 siRNAs. Moreover, in overexpressed strains there is a significa...

Organisms adopt a wide range of strategies to adapt to change. Gene silencing describes the ability of organisms to modulate the expression of susceptible genes at certain times at the transcriptional or the translational level. In all known eukaryotic organisms 21-nt long short interfering RNAs (siRNAs) are the effector molecules of post-transcriptional gene silencing (PTGS), while 24-nt long ...

Two surprising and potentially useful phenomena of transgenic plants originated from two distinct lines of research but may converge in underlying mechanism or mechanisms (1–3). Plant transformation technology, the staple of the crop biotechnology industry, overcomes the species barrier and allows introduction into plants of genes from other plant species, genes from species of other kingdoms, ...

The Sugarcane yellow leaf virus (SCYLV) P0, a member of the highly heterologous proteins of poleroviruses, is a suppressor of posttranscriptional gene silencing (PTGS) and has additional activities not seen in other P0 proteins. The P0 protein in previously tested poleroviruses (Beet western yellows virus and Cucurbit aphid-borne yellows virus), suppresses local, but not systemic, PTGS induced ...

Post-transcriptional gene silencing (PTGS) is a sequence-specific degradation mechanism that operates in almost all eukaryotic cells. In plants, double-stranded RNA triggers PTGS, generating 21- to 25-nucleotide guide RNAs responsible for specific degradation of cognate mRNA. The double stranded RNA intermediates of replicating plant viruses often induce PTGS, leading to symptom attenuation. He...